In This Guide
- C6 Vehicle Compatibility – Makes & Models
- C6 Transmission Overview
- Bell Housing Patterns
- Materials, Size & Weight
- Common Problems
- Remanufactured C6 Transmission Updates and Upgrades
- What’s Included
C6 Vehicle Compatibility – Makes & Models
- 1978–1991 Ford Bronco
- 1967–1996 Ford F-Series
- 1964–1970 Ford Fairlane
- 1966-1974 Ford Galaxie
- 1966–1980 Ford LTD
- 1977–1979 Ford LTD II
- 1966–1979 Ford Ranchero
- 1966–1979 Ford Thunderbird
- 1968–1976 Ford Torino
- 1966–1979 Lincolns
- 1966–1969 Mercury Comet
- 1967–1973 Ford Mustang
- 1967–1978 Mercury Cougar
- 1966–1972 Mercury Meteor
- 1968–1976 Mercury Montego
- 1968–1974 Mercury Monterey
- 1977 Mustang Cobra 2
C6 Transmission Overview
Produced from 1966–1996, the Ford C6 transmission is a heavy duty 3-speed automatic gearbox that saw use in some of the Blue Oval’s most popular models. It was called the “SelectShift Cruise-O-Matic” in the early days, and because of its ability to handle more torque than the C4 transmission, it was commonly used behind the big engines in full-size sedans and pickup trucks.
This was a completely mechanical automatic, so it didn’t have a lockup torque convertor or overdrive gears. The Ford C6 was also the first automatic transmission to be completely designed and built by Ford Motor Company. And it would eventually serve as the basis for Ford’s first electronically controlled heavy duty transmission, the E4OD.
The predecessor to the C6 was known as the Ford MX transmission (it was designed by Borg-Warner), and it was quite heavy (it actually had a cast-iron case) and complex. To address these issues without making their new transmission any larger, many components inside of the Ford C6 were made from powdered metal, and the transmission case was made from aluminum.
The new transmission used a much simpler 3-speed Simpson compound planetary gear set, and the C6 was the first autobox to use the Borg-Warner flexible shift band. Low and reverse gears used clutch disc plates, and there were also advanced (for the time) composite plates and valving. All of this gave the Ford C6 a maximum torque capacity of 475 lb-ft. Making it the perfect transmission for Ford to pair with their 351W, 351C, 428, 429, 460, and 462 gasoline V8’s. Along with the 7.3L diesel.
Bell Housing Patterns
Windsor / Small Block Pattern – 5-1/8” between top two bolt holes
Fits:
221ci / 3.6L V8
255ci / 4.2L V8
260ci / 4.3L V8
289ci / 4.7L V8
300ci / 4.9L I6
302ci / 4.9L (5.0) V8
335ci / 5.5L V8
351W ci / 5.8L V8 – 351 Windsor
351C ci / 5.8L V8 – 351 Cleveland
Cleveland / Big Block Pattern – 7-3/4” between top two bolt holes
Fits:
351M ci / 5.8L V8 – 351 “Big Block” or “Tall Deck”
400 ci / 6.6L V8
Ford 385 Engines –
370 ci / 6.1L V8
429 ci / 7.0L V8
460 ci / 7.5L V8
514 ci / 8.4L V8 (Ford SVO)
FE Pattern – 6” between top two bolt holes
Fits:
Ford FE Engines –
332 ci / 5.4L V8
352 ci / 5.8L V8
360 ci / 5.9L V8
361 ci / 5.9L V8
390 ci / 6.4L V8
396 ci / 6.5L V8
406 ci / 6.7L V8
410 ci / 6.7L V8
427 ci / 7.0L V8
428 ci / 7.0L V8
Diesel Pattern – Similar to the FE pattern, but not interchangeable
Fits:
420 ci / 6.9L Diesel V8
444 ci / 7.3L Diesel V8
Lincoln MEL Pattern – Similar to the FE pattern, but not interchangeable
Fits:
462 ci V8 – 1966-1968 Lincoln Continental
460 ci V8 – 1968-1970 Lincoln Continental
Due to its heavy duty design, the Ford C6 was used in a number of applications, including everything from the Ford Mustang Boss 302 & Ford LTD, to the Ford F-150 4×4 & Ford F-350 Diesel.
As a result, there were a number of variations to the case design, the pan, and the tail shaft. If you are planning to install a C6 transmission into a project vehicle, you need to make sure that it will fit your application, and that you’re using the correct torque converter.
This transmission is very popular for off-roading and drag racing, but it’s mechanical 3-speed design requires a lot of horsepower to operate. Which may reduce the fuel economy in road cars.
Materials, Size & Weight
In order to reduce weight, the Ford C6 transmission features a one-piece case design (the case and bellhousing are integrated), made from cast aluminum alloy. Over 10 lbs of powdered metal were used to make many of the internal components, which cut even more weight when compared to the cast iron Ford FMX transmission.
Thanks to these cutting-edge materials (for the 1960’s), the dry weight of a C6 transmission is 140 lbs, plus 30 lbs for the torque convertor. It requires 7-quarts of Type FA transmission fluid with the stock pan, plus an additional 2–4 quarts for the torque converter. The case length is 22-3/8”, but the overall length depends on which tailshaft housing is used – Ford cars: 14-in – Ford trucks: 7-in – Lincoln: 17.4-in.
Common Problems
No forward or reverse gear engagement
One of the most common C6 transmission problems is the complete lack of forward and/or reverse gears. The cause could be as simple as a low transmission fluid level, or a clogged transmission filter. But it could also be a stuck valve inside the valve body, a faulty torque converter, or the shift linkage may have become detached or broken.
Failed 1-2 upshift
If your C6 won’t upshift from first to second gear, then there could be a number of problems. It could be a bad governor, shift valve, servo, or one-way clutch. Many of these problems are related to age and mileage. However, shift kits and other upgrades will significantly increase the service life of your transmission.
Slipping in, out of, and/or between gears
Probably the most common C6 transmission problems are slipping between the gears, out of gear, and the hesitation to go into gear. The first thing you should check is the fluid level. If there is too much or too little transmission fluid, this problem can occur. It could also be a blocked transmission filter, a transmission pump problem, a bad vacuum modulator, a faulty torque converter, or an improperly adjusted transmission clutch / transmission band.
Ford C6 Shift Kits
If you need more performance from your C6 than the stock setup will provide, then you should consider a Ford C6 transmission kit. These are modification packages for the valve body, and are typically available in towing, performance, or racing specification.
Each one contains parts that will change the line pressure, so the transmission will have more holding power for the bands and clutches. Thus preventing slippage during extreme use conditions. Race-specific input / output shafts and hardened planetary gear sets are so available.
1st and rev is fine 2nd and 3rd feels like its not pulling out kinda like its in a bend
I need the tail shaft housing 7 to 8 inches long
I have a c6 transmission that came stock from the factory. The car is a 1973 Mustang Mach 1 Fastback. I have no info on it and would find out what it is. It was a barn find with no info available. What can I do to get more info. It seems to run ok and has only 74,469 miles on the car. Can you or someone help.
I have a C6 trans coming off of a 1978 Bronco 400 and would like to bolt it to a 351C 2v out of a 1973 ranchero would I need an adapter kit for that and do you sell it.
I have a 351 Cleveland that we pulled a four speed and replaced it with a C-6 trans using a 164 tooth flex plate. I am having trouble with starters. They crank very loud at first and then quit engaging with the flex plate. Any ideas?
I have a 1970 Ford Galaxy 4door, had no issues out of my transmission until, yesterday, I got on the interstate, rode it to about 90, exit to exit, changing out good, I got in it on the way home, from stand still, the two barrel did what I thought, but now it doesn’t want to go in park, it was just going in drive only but now it’s going to reverse but not all the way to park
1973 f 250 is leaking transmission fluid
Leaking transmission fluid
When cold it shifts from second to third but if hot or when it gets hot it shifts back into second or won’t shift into third in the first place
Can I take a c6 tranny from a 4×4 w/460 and make it useable in a E350 w/460?
C6 ford transmission won’t shift into 3rd gear but will if I let off of accerlator then shifts nice. I have 23lbs vacuum at modulator and have replaced it did not help
I had the same problem in a 1968 F250 camper special I recently did the transmission and I put the input shaft in backwards if you recently had transmission work done that would be a good reason why it will not shift if not I’m not sure maybe you just lost those gears I hope that helps you out good luck with everything
What is the spline count on a 1960s C6 for the input shaft from torque converter into the transmission,is it 31/30 or 31/31. Mine snapped in half with a portion coming out with the t. he torque converter (31 splines) and the other half still in the tranny,so couldnt count. Any help appreciated. Thx. Bob,
C6 trans. Doesnt move when put in gear, forward or reverse, fluids full
C6 approached an incline and simply fell short of going up the hill no forward or reverse dead stick…what is the possible issue or issues?
1971 C6, mated to a 460 big block, won’t shift up into third. I’m in the UK and unsure what to do and who to visit it get it solved. Kit also has a fluid leak from the front inspection type plate, I’m told from the input seal. The shift issue is my reason for commenting though
Why my transmission don’t do the third shift?
We purchased a 1997 MH with 110000 kilometers Ithaca 460 engine with a c6. I have no issues just wondering what transmission fluid is required
you can shift it manually from 3rd to first at speeds above 10mph ford had a safety feature so you could not shift it into first until 10mph orless manually. this is a rebuilt trans. How do I get that safety feature back.
I have a 1973 F250 with a C6 transmisson with a Gear Vendor overdrive. Both of which are mounted behind a 5.9 12 valve Cummins diesel which was purchased new directly from Cummins as. “crate’ engine back in 1987. Although I do believe most of this info to be unrelated to my problem, just wanted you to be totally informed
Although there were many issues to be resolved when I first purchased this truck about 5 years ago. There was one issue I didn’t even know about until I decided to remove all of the unrelated and abandoned wiring left behind after the Cummins was installed. Imagine my surprise when I noticed that the neutral safety switch had been totally removed. After acquiring a replacement and finally getting it connected properly. Everything seemed to be working properly until I was informed that one of my reverse lights was on while driving down the road. After further investigation I also realized that both of my reverse light were also not working. During the same period of time I also started to have an intermittent problem with my truck not fully shifting into to the park setting.
Although none of these issues seemed to be having any affect on the normal shifting patterns of my C6 or the overdrive. I have recently noticed that getting the truck into the park setting is getting more difficult as time goes on. I cannot say for sure if the reverse light issue is directly related but I can say if I hold left pressure on the shift lever while in the reverse gear. That my reverse lights do work as they should. So I just need a little help on which direction to go. I’m thinking “shift linkage” or maybe ” band adjustment” but to be honest I am certainly no expert on transmission problems.
So any advice and or expertise offered, will certainly be gratefully accepted and sincerely appreciated.
Please feel free to contact me directly via email at ljbaileyaz@yahoo.com
Thanks,
Larry Bailey
73F250
I am trying to locate but can’t find a transfer case adapter for a C6 3-speed transmission with four-wheel drive
C-6 transmission has no reverse and has only 1 st gear will not shift pass that, manually or regular.
rattling soud hesitation could it be convertor how do i know what convertor to get